The Physics Section is involved in studying the radiation characteristics of photon and electron beams produced by the Scanditronix MM-22 Medical Microton as part of acceptance testing and dosimetry prior to clinical use. Investigations and concurrent technical adaptations and changes have lead to flatness of the radiation fields and depth doses that are generally superior to similar beams from medical linacs. In addition, several shortcomings relative to dosimetry and specific beam characteristics were discovered and are being corrected. These include: 1. Inclusion of a dose rate compensation circuit to correct dose-rate dependence of the monitor chamber at high dose rates. 2. Modification of the dose rate servo circuits and inclusion of separate settings for the AGPS for each energy to improve dose rate stability. 3. Complete reworking of the 22 MeV electron beam. By using a thinner primary scattering foil and special secondary foil, the penetration has been substantially improved. Additionally, X-ray contamination has been markedly reduced. Also, the dosimetric aspects of asymmetric collimator jaws are being investigated. It has also been shown that their use with intraoperative applicators can virtually eliminate the "hot spot" due to the cone bevel.